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2. Slow inhibitory post-synaptic potential: a prolonged inhibitory depolarization that generate action potentials. 3. Slow excitatory post-synaptic potential: a prolonged excitatory depolarization that generate action potentials. 4. Late slow excitatory post-synaptic potential: It is very prolonged, lasting minutes rather than milliseconds. Fast and slow responses of postganglionic neurons in sympathetic ganglia Potential Duration Mediator Receptor Fast EPSP 30 msec Acetylcholine Nicotinic cholinergic Slow IPSP 2 sec Dopamine D2 Slow EPSP 30 sec Acetylcholine M1 -cholinergic Late slow EPSP 4 min GnRH GnRH D2 , dopamine receptor inhibiting adenylate cyclase through inhibitory G protein; EPSP, excitatory postsynaptic potential; GnRH, gonadotropin-releasing hormone; IPSP, inhibitory postsynaptic potential. These slow responses apparently modulate and regulate transmission through the sympathetic ganglia. Cholinergic discharge: In general way, the functions promoted by activity in the cholinergic division of the autonomic nervous system are those concerned with vegetative aspects of day-today living. For example, cholinergic action favors digestion and absorption of food by increasing the activity of the intestinal musculature, increase gastric secretion, and relaxation of the pyloric sphincter. For this reason, and contrast it with the âcatabolicâ noradrenergic division, the cholinergic division is sometimes called the âanabolic nervous systemâ. Nor-adrenergic discharge: The nor-adrenergic division discharge as a unit in emergency situation. The effects of this discharge are of considerable value in preparing the individual to cope with the emergency, although it is important to avoid the teleological fallacy in the statement that is the system discharge in order to do this. For example, noradrenergic discharge: ï¥ Relaxes accommodation and dilates the pupils (letting more light into the eye). ï¥ Accelerates the heart-beat and raise the blood pressure (providing better perfusion of the vital organs and muscles). ï¥ Constricts the blood vessels of the skin (which limits bleeding from wound). ï¥ Lower thresholds in the reticular formation (reinforcing the alert, aroused state) 10
